Flow elements for use with flexible spinal needles, needle assemblies and methods therefor

Abstract

A flow element for use with flexible needles and flexible needle assemblies to minimize flow occlusion within a flexible needle is provided. The flow element is particularly suited for uses with a flexible needle for minimizing incidence of post-dural puncture headache. The flow element includes a body having an internal flow path for conducting a fluid through a flexible needle, and an anti-restriction member. The anti-restriction member includes an elongated body, a proximal end coupled to the body within the internal flow path, and a distal end for disposing at least a portion of the elongated body within a flexible needle. A flexible spinal needle assembly for minimizing flow occlusion through an internal flow path of a flexible needle by unintended kinking that is potentially caused by ligament or muscle layer movements is also provided.

1. A flexible spinal needle assembly adapted for minimizing flow occlusion through a lumen of a flexible needle when inserted into a subject, the flexible spinal needle assembly comprising:
 a flexible needle comprising:
 a lumen; 
 a distal end comprising a tip and an opening located proximate to the tip; and 
 at least one radially reinforcing element to maintain structural integrity of the flexible needle during insertion into the subject; and 
 
 a flow element adapted for use with the flexible needle previously inserted within the subject, the flow element comprising:
 a flow element body having an internal flow path adapted for conducting a fluid into the lumen of the flexible needle, the flow element body having structure adapted for coupling the flow element body to the flexible needle to position the internal flow path in fluid communication with the lumen; 
 
 a conduit, secured to the flow element body and couplable to a supply of fluid, the conduit being in fluid communication with the internal flow path adapted for supplying a quantity of fluid to the internal flow path; and 
 an anti-restriction member having an elongated body comprising at least one freely extending wire, a proximal end coupled to the flow element body within the internal flow path, and a distal end formed by a terminal end of the at least one wire adapted for inserting at least a portion of the elongated body within the flexible needle after the flexible needle has been inserted within the subject, the terminal end of the at least one wire being sized and adapted to extend freely to a location proximate to the distal end of the flexible needle when the anti-restriction member is disposed in the flexible needle, the anti-restriction member being adapted for placement within the lumen of the flexible needle to permit fluid flow through the lumen while the anti-restriction member is resident within the lumen, the anti-restriction member functioning to resist occlusion of the fluid flow through the lumen resulting from a kinkage of the flexible needle. 
 
     
     
       2. The flexible spinal needle assembly of  claim 1 , wherein the flow element body is made from a medical grade plastic, the anti-restriction member is made from a medical grade stainless steel and the flow element body includes a cylindrical outer surface extending substantially between a first end and a second end, wherein a portion of the cylindrical outer surface is configured for sealing attachment to an attachment structure of the flexible needle. 
     
     
       3. The flexible spinal needle assembly of  claim 2 , wherein the conduit is coupled to the first end of the flow element body and a support hub coupled to the flow element body, the support hub having a first attachment structure configured to removably attach to the flexible needle while positioning at least a portion of the elongated body therein, the first attachment structure comprises a luer lock type connector. 
     
     
       4. The flexible spinal needle assembly of  claim 1 , wherein the elongated body of the anti-restriction member comprises at least two wires forming a freely extending set of wires. 
     
     
       5. The flexible spinal needle assembly of  claim 4 , wherein the elongated body of the anti-restriction member comprises six wires. 
     
     
       6. The flexible spinal needle assembly of  claim 1 , wherein the anti-restriction member comprises a plurality of elongated bodies. 
     
     
       7. The flexible spinal needle assembly of  claim 1 , wherein the elongated body of the anti-restriction member comprises at least two wires forming a freely extending set of twisted wires. 
     
     
       8. The flexible spinal needle assembly of  claim 1 , wherein the elongated body of the anti-restriction member comprises at least two wires forming a freely extending set of wires that are secured distally with a weld bead. 
     
     
       9. The flexible spinal needle assembly of  claim 1 , wherein the distal end of the elongated body protrudes from a flexible distal end of the flexible needle, the flexible needle is configured having an outside diameter sized so that withdrawal of the flexible needle from dura mater of a spine, subsequent to insertion of the flexible needle assembly through the dura mater, permits the dura mater substantially to reseal a space formerly occupied by the flexible needle, the elongated body of the anti-restriction member is configured for substantially preventing partial occlusion of the lumen, and the flexible needle is configured for being slidably mounted on a portion of a support needle such that a first end of the support needle protrudes from the flexible needle exposing a non-cutting piercing point for allowing the flexible needle and the support needle to be inserted through the dura mater and into the intrathecal space of a subject and, upon removal of the support needle, is configured for disposing a portion of the anti-restriction member within the flexible needle. 
     
     
       10. The flexible spinal needle assembly of  claim 9 , wherein a flexible needle body of the flexible needle is of such substantial axial extent to be further extendable into the dura mater upon extraction of the support needle, and the flow element body comprises a support hub having a first attach structure, and a proximal end of the flexible needle carries a flexible needle hub having a second attach structure configured to removably attach to the first attach structure carried by the support hub. 
     
     
       11. The flexible spinal needle assembly of  claim 10 , wherein the flexible needle body comprises a cannula formed from a first material and radially reinforced over an extent toward a distal portion of the lumen by a second material comprising a stainless steel ribbon spring and further comprises a kink sleeve disposed on a portion of the flexible needle hub and over a portion of the cannula of the flexible needle. 
     
     
       12. The flexible spinal needle assembly of  claim 1  wherein the flexible needle has an exterior diameter such that withdrawal of the flexible needle from dura mater, subsequent to insertion of the flexible spinal needle assembly therethrough, permits the dura mater substantially to reseal a space formerly occupied by the flexible needle, and the tip and a flexible needle body of the flexible needle are of substantial elongated extent to be further extendable into the dura mater upon extraction of a support needle coupled therewithin before exposing the flow element therewithin, and wherein the flow element is configured for attachment to medical fluid transfer equipment having structure to form a luer lock type connection. 
     
     
       13. The flexible spinal needle assembly of  claim 1  wherein: the flexible needle has a flexible needle body comprising an elongated hollow tube having the lumen formed therein; and
 wherein the terminal end of the at least one wire is in direct contact with an inner portion of the flexible needle in the lumen. 
 
     
     
       14. The flexible spinal needle assembly of  claim 13 , comprising a flexible spinal needle assembly kit comprising a prepackaged and sterilized assembly comprising the flow element and the flexible needle. 
     
     
       15. The flexible spinal needle assembly kit of  claim 14 , further comprising a support needle configured for insertion into the flexible needle and to minimize the transverse flexibility of the flexible needle to enable insertion of the support needle and coaxially supported flexible needle through dura mater and into a spine of a subject, and a central stylet configured for removable insertion into the support needle to prevent entry of matter through an opening proximate a distal end of the support needle when inserted into the subject, wherein the support needle and the flexible needle are pre-assembled allowing insertion of the pre-assembly into the subject facilitating removal of the support needle and subsequent insertion of the flow element into the flexible needle. 
     
     
       16. The flexible spinal needle assembly of  claim 1 , wherein the at least one radially reinforcing element comprises a structure formed within the flexible needle. 
     
     
       17. The flexible spinal needle assembly of  claim 16 , wherein the at least one radially reinforcing element comprises at least one of an internal wire wrap and an internal spring. 
     
     
       18. The flexible spinal needle assembly of  claim 1 , wherein the at least one radially reinforcing element comprises an external wire wrap. 
     
     
       19. A process for producing the flow element of the flexible spinal needle assembly of  claim 1 , the process comprising:
 forming the anti-restriction member having the elongated body, the proximal end and the distal end, the elongated body configured for disposing at least a portion thereof by way of the distal end within the flexible needle; and 
 securing the proximal end of the anti-restriction member to the flow element body having the internal flow path for conducting a fluid through the flexible needle. 
 
     
     
       20. The process for producing a flow element of  claim 19 , wherein securing the proximal end of the anti-restriction member to the flow element body comprises injection molding the flow element body about the proximal end of the anti-restriction member, and forming the anti-restriction member having the elongated body comprises forming the anti-restriction member with a plurality of elongated bodies, at least one elongated body comprising a plurality of wires. 
     
     
       21. A flow element for use with a flexible needle previously inserted and remaining within a patient, the flow element comprising:
 a flow element body having an internal flow path for conducting a fluid into a lumen of the flexible needle, the flow element body having structure for coupling the flow element body to the flexible needle to position the internal flow path in fluid communication with the lumen; 
 a conduit, secured to the flow element body and couplable to a supply of fluid, the conduit being in fluid communication with the internal flow path for supplying a quantity of fluid to the internal flow path; and 
 an anti-restriction member having an elongated body comprising a freely extending twisted set of wires formed by at least two wires, a proximal end coupled to the flow element body within the internal flow path, and a distal end formed by terminal ends of the at least two wires, the terminal ends of the at least two wires being sized and adapted to extend freely to a location proximate to a distal end of the flexible needle, the anti-restriction member being configured for insertion within the lumen of the flexible needle after the flexible needle has been inserted in the patient to permit fluid flow through the lumen while the anti-restriction member is resident within the lumen, the anti-restriction member functioning to resist occlusion of the fluid flow through the lumen resulting from a kinkage of the flexible needle. 
 
     
     
       22. A flexible spinal needle assembly for minimizing flow occlusion through a lumen of a flexible needle when inserted into a subject, the flexible spinal needle assembly comprising:
 a flexible needle including a lumen; and 
 a flow element for use with the flexible needle previously inserted within a patient, the flow element comprising:
 a flow element body having an internal flow path for conducting a fluid into the lumen of the flexible needle, the flow element body having structure for coupling the flow element body to the flexible needle to position the internal flow path in fluid communication with the lumen; 
 
 a conduit, secured to the flow element body and couplable to a supply of fluid, the conduit being in fluid communication with the internal flow path for supplying a quantity of fluid to the internal flow path; and 
 an anti-restriction member having an elongated body comprising a freely extending set of wires formed by at least two wires, each of the at least two wires having a terminal end being sized and adapted to extend freely to a location proximate to a distal end of the flexible needle, a proximal end of the anti-restriction member coupled to the flow element body within the internal flow path, and a distal end of the anti-restriction member formed by the terminal end of each of the at least two wires and configured for inserting at least a portion of the elongated body within the flexible needle after the flexible needle has been inserted within the patient, the anti-restriction member being configured for placement within the lumen of the flexible needle to permit fluid flow through the lumen while the anti-restriction member is resident within the lumen, the anti-restriction member functioning to resist occlusion of the fluid flow through the lumen resulting from a kinkage of the flexible needle.